Still playing Dark Souls on the PC? Hey, I don't blame you, it's a good game. However, if you would like to ensure your progress and achievements are moved over from Games for Windows Live to Steamworks, there are some important steps you need to do prior to February 16.

A new announcement on the Dark Souls community page at Steam gives detailed instructions on how to move your game over to Steam without any hassle. I will paste only the instructions below for those that have the game on Steam already. However, they also provide instructions for those who have the game via retail (disc) or who purchased through GFWL Marketplace directly (digital). For those special cases, head on over to the Community page for the additional details.
For users who purchased a Game for Windows live version from Steam prior to December 15:If you purchased the game through Steam after December 15 all you need to do is:

If you purchase the game after February 16, 2015, you don't have to worry about doing anything extra. It should be noted that those using DSFix might run into some issues if you're altering the framerate at all. An updated version of DSFix (2.3) was released today that should address any issues that came up as a result of migrating to Steam.